The need for methods to produce high-precision arrays of miniature and micro lenses has been driven in part by the development of high speed optical switches and optical couplers commonly used in telecommunications equipment, as well as the development of advanced high speed optoelectronics and instrumentation. In one non-limiting exemplary application, it is desired to maintain a center to center spacing of 250 μm within a positioning error of 2 μm, in a four by four array of sixteen micro lenslets comprising hyperbolic aspheres having apertures of 220 μm.
The present methods were developed to exceed these specifications through a unique positioning and indexing approach that allows a workpiece to be indexably positioned and re-positioned in two (e.g. orthogonal) directions parallel to the rotating spindle face of a machine tool. The methods utilize matching sets of inter-fitting locating grooves that can be cut or scribed into a workpiece, and a workpiece holder affixed to the spindle face of a machine tool. The workpiece can then be positioned and re-positioned by distances equal to an integral number of groove spacings in one or more directions parallel to the surface of the workpiece, to precisely and non-kinematically determined locations. At each location a curved feature (e.g. lens shape, lens mold shape, cylinder, cone etc.) can then be on-center machined into the surface of the workpiece. The use of a plurality of inter-fitting locating grooves provides an averaging effect to minimize any positional errors that may occur, thereby affording a high level of repeatability and precision in locating the relative centers of the curved features in an array thus produced.